1. Field of the Invention
The present invention relates to a mobile phone, and more particularly to an apparatus for supplying power to a mobile phone by utilizing an external power source.
2. Description of the Related Art
According to continuous development and progress in wireless communication technology and semiconductor manufacturing technology, mobile phones are growing lighter and more compact and coming to have more functions. Actually, a mobile phone is nowadays an indispensable communication appliance in daily life. However, it is very inconvenient and even dangerous for a user to perform communication with a mobile phone in his or her hand in some situations. For example, it is potentially very dangerous for a person to communicate while driving with a mobile phone in his or her hand. Therefore, most mobile phones are provided with an earphone-microphone connector which can be connected with an external earphone-microphone set. The earphone-microphone connector is usually a connector socket which has standardized dimension and shape.
FIG. 1 is a diagram illustrating an electric construction of a conventional earphone-microphone set.
Referring to FIG. 1, the conventional earphone-microphone set includes an earphone 7, a microphone 6, and a plug 5, and the plug 5 includes four electrical nodes 1, 2, 3, and 4. One end of the earphone 7 is connected with the node 1, and the other end of the earphone 7 is connected with the node 4. Further, one end of the microphone 6 is connected with the node 2, and the other end of the microphone 6 is connected with the node 3. The plug 5 has a construction suitable for insertion into a socket-type earphone-microphone connector provided at a mobile phone.
FIG. 2 is a diagram illustrating an internal construction of a conventional earphone-microphone connector socket in a usual mobile phone, and FIG. 3 is a diagram schematically illustrating an internal circuit of the earphone-microphone connector socket shown in FIG. 2.
As shown, the earphone-microphone connector socket 10 includes four internal contacts 11, 12, 15, and 16, which can be connected with the corresponding nodes 2, 1, 3, and 4 of the earphone-microphone set shown in FIG. 1, respectively, and additional internal contacts 13 and 14 which are used in detecting the insertion of the earphone-microphone set into the earphone-microphone connector socket.
Referring to FIG. 3, when the earphone-microphone set is not inserted in the earphone-microphone connector socket, the internal contact 13 is physically short-circuited to the internal contact 12 while the internal contact 14 is physically short-circuited to the internal contact 15. In FIG. 3, this short-circuited state is represented by arrows of the internal contacts 13 and 14 in contact with the internal contacts 12 and 15, respectively. In this case, the internal contacts 13 and 16 are connected with a speaker on the mobile phone body, and the internal contacts 11 and 14 are connected with a microphone on the mobile phone body.
In this case, most of the voltage AVcc is applied to the microphone of the mobile phone body, which has a relatively large resistance of about 2.2 kΩ, so that the internal contact 14 is maintained in the LOW state. As a result, an NPN Field Effect Transistor (FET) Q, which has a gate input G1, a source S1, and a drain D1, is utilized as follows. When the gate input G1, which is a status signal of the internal contact 14, is off, and the signal JACK_IN supplied to a control section or coder/decoder (CODEC) of the mobile phone, is shifted to the HIGH state by the voltage Vdd, the signal JACK_IN maintains the mobile phone in a general communication mode, and not in a communication mode, where the user communicates through the earphone-microphone set.
When the plug 5 of the earphone-microphone set, which has the nodes 1, 2, 3, and 4 as shown in FIG. 1, is inserted in the earphone-microphone connector socket 10, the force of the inserted plug separates the internal contact 13 from the internal contact 12 and the internal contact 14 from the internal contact 15, thereby disconnecting the internal contact 12 and the internal contact 15 from the speaker and the microphone of the mobile phone body, respectively. Simultaneously, the internal contacts 12 and 16 are connected with the earphone 7 through the nodes 1 and 4, and the internal contacts 11 and 15 are connected with the microphone 6 through the nodes 2 and 3. In this case, the internal contact 14 is shifted to the HIGH state by a pull-up resistor R1 between the internal contact 14 and AVcc. Therefore, the signal JACK_IN is connected with the ground through the drain D1 and source S1 of the NPN Field Effect Transistor Q, the gate input G1 of which is connected to the a status signal of the internal contact 14, so that the signal JACK_IN shifts to the LOW state. The signal JACK_IN shifts the mobile phone into the communication mode through the earphone-microphone set.
As explained above, the function of the conventional earphone-microphone connector is to connect the earphone-microphone set and the mobile phone. Typically, the earphone-microphone connector does not perform any other function. As explained above, once this connection is made the mobile phone can be operated in the communication mode, which leaves the user's hands free to perform other tasks.
In the meantime, most mobile phones employ a rechargeable battery as an electric power source to provide portability. However, the rechargeable battery has limited capacity, depending on the kind and lifespan of the battery. Accordingly, the mobile phone cannot be used once the battery is discharged. Moreover, since the batteries of mobile phones usually have different shapes and power capacities, according to manufacturer and model of the battery, it is almost impossible for a mobile phone to utilize a different battery from another mobile phone in place of its own battery. In order to solve this problem, there have been various efforts and research into developing a technology which can enable a mobile phone to be recharged regardless of the kind of the battery used. However, it is still a common case that a user of a mobile phone cannot recharge the battery of the mobile phone, due to his or her situation or location. In this case, the user cannot help using a public phone or borrowing another person's mobile phone.